It's a move many perfect this time a year the old credit -- swipe turning over a mountain. A financial details of the flick of wrist and -- keep you swiping. And their bottom line growing credit card companies have to maintain your trust trust that they are smarter than any hacker Fisher or sketchy clerk. And to that -- -- that gave us an unprecedented glimpse into their fortress of security. And a few tips to stay one have one step ahead of the crooks here's ABC's Cecilia Vega. Tis the season -- credit card fraud. For all kinds of people to find all kinds of -- and steal your credits and spend it. Last year about eight million Americans were victims almost half of those due to stolen credit information. And it doesn't end there. You might not realize it but one of the cards most vulnerable to credit theft are those gift cards everyone loves to give and -- Thieves find -- easy to steal and it's entirely possible when the recipient goes to use the gift card you've given your won't be any money left on it. When they see a gift card on -- display at what they'll often do is they can skim the information off the back of the magnetic strip. And once they do that they have enough information about that card. That they can go ahead and Depp -- in order over the Internet or even over the phone they can also clone that card and use it at any retailer. And while most of us believe that online shopping makes us more susceptible to fraud. We learned that using cards in stores is actually a greater -- Whereas when you walk into a brick and mortar retailer you're heading that credit card to a human human steel. And so when you handed to them they can easily -- the information -- that card in use -- a fraudulent activity. If you're worried so -- the credit card companies and so Nightline -- first time ever access to a top secret facility where one company. These has been watching every single -- getting made this holiday season. I'm here to see -- after -- -- here. The facility so top secret it doesn't appear on Google Maps and we are not allowed to tell you where it is an -- -- -- -- I had to pass through more security here than I do what I'm covering the White House. Motion sensors cameras. And everything else in this I would. Mike Pryor is -- global head of technology he takes me the first line of defense what -- calls the man trapped. No one makes it through without a special badge and -- fingerprint match. That's because what lies on the other side is hacker's dream and an identity theft victim's nightmare. And the heart of one of the country's largest credit and debit card companies is revealed. How many has actually going on right now as we speak. Just almost 8000 transactions. And that's globally that's global and there are all being processed right here through this all -- -- -- justice. Employees here spend their days fixated on this wall of monitors. Watching everything from the news to the weather looking for any -- any abnormality that could bring it all crashing down. Hence the need for men trapped number two. A concrete room with motion detectors a camera on the ceiling that reads handwriting on scraps of Paper. It even -- a radio frequencies that can catch anyone trying to bring in a forbidden cell phone. And what happens if someone tries for a -- getting out the other as the name. I think there's yeah. There are enough cables inside to stretch all the way from Maine to Key West and -- -- credit card swipe. Before it's even done before you walk out with your purchase transactions are routed into this room -- -- -- my credit card combine that cup of coffee. This is where that goes so that I'm getting cars -- -- -- work. The stakeholders. The information they need to -- ahead of the moment there are a lot of eyes watching. A lot a lot more than behind him. Along the building is strong enough to withstand a major earthquake or a tornado. It has its own water treatment system and generates enough power to support 25000. Homeless -- got. A -- yes you've got. Multiple layers of fences to keep people -- ice not cameras almost every five feet inside this building their security guards you're not get in here is all this necessarily is necessary is necessary to keep your transactions safe and secure. The power goes out batteries again generators after that. It's so far so good. All the precautions some might call it paranoia has paid off human or otherwise nothing has managed to put a dent in -- -- -- It is something that we want to make sure that that you don't have to think about -- are using their cards note that the court decision secure. It won't be might be secured the average shopper should still know how to keep their plastic protected. So we identity theft expert Robert Cecelia -- forced on tips for those last minute gift cars. If you buy gift cards I recommend buying them at say a mall kiosk. Where one person behind that counter is responsible for. Administering that card when using -- -- classic. You have to pay very close attention to your credit card statement and refute any unauthorized charges with in a sixty day period of time. And -- shopping online. The most important thing to do is to make sure that the web -- they're using is a secure one. That means that in the address bar where it says HTTP. It should say HTTP -- that means -- it's a secure encrypted site. And if all else fails contact your credit card company just don't expect to get through the front doors. For Nightline -- Cecilia Vega reporting well like I said I can't tell you where.

This transcript has been automatically generated and may not be 100% accurate.

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